Fuser system for copying machine

ABSTRACT

Fusing apparatus for heating developed images on copy sheets moving through an automatic copying machine at variable rates including a conveyor for transporting copy sheets having fusible images thereon at variable rates past a plurality of heater elements, a first circuit for generating ramp signals at a predetermined duration, and a second circuit including a thermistor responsive to changes in temperature and at least two voltage dividing networks each corresponding to a different fusing temperature. A zero cross pulse generator and comparator responsive to input signals from said first and second circuits emits signals when the output signals of said first circuit means exceeds that of said second means and a third circuit including at least one triac coupled to at least a portion of said heater elements receives signals from said zero cross pulse generator and comparator and applies power to said heater elements in accordance with a preselected copy travel rate.

United States Patent [72] Inventor Gary L. Schluntz Penfield,N.Y. [21] AppLNo. 824,540 [22] Filed May 14,1969 [45] Patented Jan.26, 1971 [73] Assignee Xerox Corporation Rochester, N.Y. a corporation of New York [54] FUSER SYSTEM FOR COPYING MACHINE 5 Claims, 54 Drawing Figs.

[52] U.S.Cl 219/216, 219/388,219/497,219/505 [51] lnt.Cl G03g 13/20 H051) H02 7 [50] FieldotSearch 219/216,

[56] References Cited UNITED STATES PATENTS 1,896,953 2/1933 Hassell 165/46 1,905,439 4/1933 Carleton 2l9/297X 2,259,401 10/1941 Tucker et alm. 219/297 2,418,283 4/1947 Wilson 219/354X 2,511,635 6/1950 Holmes 219/297 2,710,908 6/1955 Doniak.... 2191298X 2,753,435 7/1956 .lepson..... 219/212X 2,825,791 3/1958 Jackson 2l9/365X 2,982.841 5/1961 MacCracken 2l9/212X I l l l L I 1 L I 3,227,208 l/1966 Potter et al. 219/325(UX) 3,402,709 9/ l 968 Shivers et al l65/46X FOREIGN PATENTS 402,088 1 l/ 1 933 Great Britain 128/400 861,633 2/1961 Great Britain 219/321 1,072,376 6/1967 Great Britain 219/528 Primary Examiner- Joseph V. Truhe Assistant Examiner-Peter W. Gowdey Att9rneysPaul M. Enlow, Norman E, Schrader, James J.

Ralabate, Ronald Zibelli and Melvin A. Klein ABSTRACT: Fusing apparatus for heating developed images on copy sheets moving through an automatic copying machine at variable rates including a conveyor for transporting copy sheets having fusible images thereon at variable rates past a plurality of heater elements, a first circuit for generating ramp signals at a predetermined duration, and a second circuit including a thermistor responsive to changes in temperature and at least two voltage dividing networks each corresponding to a different fusing temperature. A zero cross pulse generator and comparator responsive to input signals from said first and second circuits emits signals when the output signals of said first circuit means exceeds that of said second means and a third circuit including at least one triac coupled to at least a portion of said heater elements receives signals from said zero cross pulse generator and comparator and applies power to said heater elements in accordance with a preselected copy travel rate.

PATENTEU m2 6 l9?! sum 01 0F 33 INVENTOR. GARY L. SCHLUNTZ BY WMAMMZM A T TORNEY PATENTEUJANZBIQYI 3.558.853

snm on HF 33 Top CENTER Oslo AUTO LOWER M Q MM 4 PATENTED JAN26 l9?! sum as or 33 PATENTEDJAN28|97| 3558.853 7 saw 09m 33 I Il ll PATENTED JAN 2 6 I97] SHEET 11 0F 33 PATENTEU JANZGIQYI' sum 13 or 33 FIG. 20a

PATENIEn Jmzslsn SHEET l HF 33 PMEMEnJANZsIQn 3,558,853

sum 15 or 33 PATENTEU JAN26 lsm' SHEET 18 0F 33 

1. Fusing apparatus for fusing developed images on copy sheets moved through an automatic copying machine at variable rates comprising: means for transporting copy sheets having fusible developed images thereon at variable rates past a plurality of heater elements, first circuit means for generating ramp signals of a predetermined duration, second circuit means including a thermistor responsive to changes in temperature and at least two voltage dividing networks each corresponding to a different fusing rate to emit reference signals indicative of a proper fusing temperature, pulse generator and comparator means responsive to input signals from said first and second circuit means to emit signals when the output signals of said first circuit means exceeds that of said second means and third circuit means including at least one triac coupled to at least a portion of said heater elements to receive signals from said pulse generator and comparator means and apply power to said heater elements in accordance with a preselected copy travel rate.
 2. Apparatus according to claim 1 wherein said thermistor is positioned below the copy sheet travel path on a support member, and control means to move said support member toward and away from the travel path.
 3. Apparatus according to claim 1 including circuit means for indicating a ready-print state to machine control when a proper temperature level of said heater elements is established.
 4. Apparatus according to claim 4 including circuit means to override output signals from said second circuit means when an open thermistor condition exists.
 5. Apparatus according to claim 1 wherein said first circuit means includes control means to effect different temperature levels for accommodating varying copy sheet stock and changes in ambient conditions. 